1. Field of the Invention
The present invention relates to a reactor and a reactor manufacturing method, and a power converter including the same reactor. In particular, the present invention relates to a reactor incorporated in the power converter of an electric vehicle, and a manufacturing method of the same.
2. Description of Related Art
The reactor is a passive element which is used for improvement of power factor, suppression of harmonic current, smoothing of direct current and the like in an electric circuit. The reactor is also sometimes used as a component of a voltage converter which raises/lowers DC voltage. The reactor may be called “inductor”.
The reactor is used for an electric vehicle as well. The electric vehicle includes a motor which acts as a driving source and the reactor is used in an electric circuit for a motor thereof. The electric circuit includes an inverter circuit and a voltage converter circuit. In a specific type of the electric vehicle, a driving voltage of the motor is higher than an output voltage of a battery and therefore, the voltage converter for raising the output voltage of the battery is provided prior to the inverter circuit. In this specification, a motor drive unit which includes the inverter circuit and the voltage converter circuit is called power converter or power control unit (referred to as PCU).
The reactor is an element which is likely to generate heat. Particularly, a circuit which handles a large current as in the electric vehicle generates a large amount of heat. Thus, a temperature sensor may be installed to monitor a temperature of the reactor (Japanese Patent Application Publication No. 2010-203998 (JP 2010-203998 A), Japanese Patent Application Publication No. 2010-219251 (JP 2010-219251 A), Japanese Patent Application Publication No. 2009-267360 (JP 2009-267360 A), Japanese Patent Application Publication No. 2010-219251 (JP 2010-219251 A), and Japanese Patent Application Publication No. 09-229775 (JP 09-229775A)).
A technology disclosed in JP 2010-203998 A is as follows. A reactor includes a ring-like core having parallel portions. A bobbin is mounted on each parallel portion and then, coil is wound around the bobbins. The two bobbins have a flange at each end and are connected to each other by the flange. Partition walls extend from the flanges in order to partition between the two bobbins. The partition wall is provided with a slit and a temperature sensor is provided within the slit.
In a reactor disclosed in JP 2010-219251 A, coils are also wound around parallel portions of a core. The two coils are covered with resin and a hole is made in resin between the two coils. A temperature sensor is embedded in the hole in the resin. According to technology disclosed in JP 2009-267360 A, a hole is made in a core and a temperature sensor is installed in the hole. In reactors disclosed in JP 2010-219251 A and JP 09-267360 A, a part of the coil is covered with resin and a temperature sensor is embedded in the hole provided in the resin.